Method for reading and writing an incompletely recordable optical disk

ABSTRACT

A record carrier includes write status information indicating whether at least one area of the record carrier has been written, initial area status information indicating the extent of an uninterrupted initial area contiguously written from the start of a track pattern area intended for writing information blocks, and/or conformance status information indicating whether the record carrier is written to fully comply with the requirements of a standard that specifies requirements of reading devices or only partially complies with the standard for reading devices.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of application Ser. No. 08/972,756 filed Nov. 18,1997 now U.S. Pat. No. 6,151,281.

FIELD OF THE INVENTION

The invention relates to the field of devices for optical, recording ona record carrier.

BACKGROUND OF THE INVENTION

The invention relates to a device for writing information blocks in atrack pattern on a record carrier of a writable type, which device isprovided with a write unit for writing areas of the record carrier via(i.e. by using) a beam of electromagnetic radiation with marksrepresenting the information blocks, and positioning means forpositioning the write unit on depending on a track structure whichindicates the position of the track pattern on the record carrier.

The invention also relates to a writable record carrier having a trackpattern for writing information blocks, and a track structure whichindicates the position of the track pattern.

The invention also relates to a method of writing information blocks ina track pattern on a record carrier of the writable type. Marksrepresenting the information blocks are written in areas of the recordcarrier via a write unit and a beam of electromagnetic radiation. Thewrite unit is positioned depending on a track structure which indicatesthe position of the track pattern.

The invention also relates to a reading device for information blocksrepresented by optically readable marks in a track pattern on a recordcarrier. The device is provided with a read unit for reading the marksvia a beam of electromagnetic radiation, and apparatus for positioningthe read unit on the basis of the marks.

A writing device, a method and a record carrier of the type described inthe opening paragraph for writing information blocks are known from U.S.Pat. No. 4,901,300 (PHN 12.398). In the system described in thatdocument, information blocks are written in a track pattern on therecord carrier and represented by optically readable marks. The recordcarrier has a track structure in the form of a wobbling pregroove with avarying frequency which represents position information. The writingdevice has a write head for scanning the record carrier via a beam ofelectromagnetic radiation. The tracking signals are derived fromreflected radiation, and apparatus for positioning the write head duringscanning based on the position information. During scanning, amodulation in the tracking signals is produced by the wobble. Thismodulation includes the position information encoded therein, indicatingthe absolute position in the track with respect to the starting point ofthe area intended for information. The information blocks are written onthe record carrier at a desired position in conformity with theiraddress, while, if necessary, the write head is positioned via a jump toanother radial position in the track on the basis of the positioninformation. A record carrier may be partly written and then includeswritten areas in which marks are present, and unwritten areas in whichonly the track structure is present. Reading devices are known whichderive the tracking signals and/or position information only from themarks. Those skilled in the art are directed to EP 9 328 240 regardingsuccessive formatting. The above citations are hereby incorporatedherein in whole by reference.

SUMMARY OF THE INVENTION

The inventor recognizes that no position information can be generated inunwritten areas, so that a partly written record carrier is not reliablyreadable.

It is an object of the invention to provide apparatus with which apartly written record carrier can be read in a more reliable manner.

In accordance with a first aspect of the invention, a writing device asdescribed in the opening paragraph is therefore characterized in thatthe device is provided with status apparatus for generating statusinformation which is indicative of the fact that at least one area ofthe record carrier has been written. The status information includesinitial-area information which indicates the position of anuninterrupted written initial area which extends from the start of atrack pattern area intended for writing information blocks.

In accordance with a second aspect of the invention, a record carrier asdescribed in the opening paragraph is characterized in that the recordcarrier is provided with status information which indicates that atleast one area of the record carrier has been written. The statusinformation includes initial-area information which indicates theposition of an uninterrupted written initial area which extends from thestart of a track pattern area intended for writing information blocks.

In accordance with a third aspect of the invention, a method asdescribed in the opening paragraph is characterized in that statusinformation is generated which indicates that at least one area of therecord carrier has been written. The status information includesinitial-area information which indicates the position of anuninterrupted written initial area which extends from the start of atrack pattern area intended for writing information blocks.

In accordance with a fourth aspect of the invention, a reading device asdescribed in the opening paragraph is characterized in that thepositioning apparatus are adapted (i.e. have structures to enable it) toposition depending upon status information which indicates that at leastone area of the record carrier has been written. The status informationincludes initial-area information which indicates an uninterruptedwritten initial area which extends from the start of a track patternarea intended for writing information blocks.

The inventive measures have, inter alia, the advantage that the readingdevice only needs to be adapted (i.e. structurally modified to enableit) in a limited way and does not need to be provided with complex meansfor regaining position information on the basis of the track structure.

An embodiment of the writing device according to the invention ischaracterized in that the device is provided with rewriting apparatusfor rewriting, contiguously to the initial area, information blockswhich are isolated from the initial area. This has the advantage thatthe isolated information blocks can be read with a simple, standardreading device because a copy is available within the initial area.

An embodiment of the reading device according to the invention ischaracterized in that the positioning apparatus are adapted to rejectinstructions for positioning outside the initial area. This has theadvantage that the reading device prevents the read head from reachingan unwritten area whereby the reading device would come in an undefinedstate.

Those skilled in the art will understand the invention and additionalobjects and advantages of the invention by studying the description ofpreferred embodiments below with reference to the following drawingswhich illustrate the features of the appended claims:

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1a-1 d shows a record carrier having a track structure.

FIG. 2 shows a partly written record carrier with status informationaccording to the invention.

FIG. 3a-3 b shows a partly written record carrier with rewritteninformation blocks according to specific embodiments of the invention.

FIG. 4 shows a writing device for writing information blocks.

FIG. 5 shows a reading device for reading information blocks.

In the Figures, elements corresponding to those elements alreadydescribed have the same reference numerals.

FIG. 6 shows additional details of the positioner of FIG. 4.

FIG. 7 shows additional details of the system drive unit of FIG. 4.

FIG. 8 shows a network for implementing the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1a shows a disc-shaped record carrier 1 having a track 9 intendedfor writing and a central aperture 10. The track 9 is arranged inaccordance with a spiral pattern of turns 3. The position of track 9 isindicated on the record carrier by a track structure provided duringmanufacture of the blank record carrier. FIG. 1b shows a cross-sectiontaken on the line b—b of the record carrier 1, in which a transparentsubstrate 5 is provided with a recording layer 6 and a protective layer7. The track structure is constituted, for example, by a pregroove 4which enables a write head to follow the track 9 during scanning. Thepregroove 4 may be implemented as an indentation or an elevation, or asa material property different from its surroundings. The track structuremay also consist of an alternation of elevated and deeper turns,referred to as land and groove patterns, with a transition from land togroove or vice versa taking place per turn. The recording layer 6 may beoptically or magneto-optically writable by means of a device for writinginformation such as the known CD-Recordable. The information isorganized in information blocks and is represented by optically readablemarks 11 in the form of a succession of areas reflecting large and smallquantities of radiation such as, for example, a succession of pits ofdifferent lengths in a CD. Such a writable disc is provided in thesystem of the novel high density optical disc, the Digital VersatileDisc (DVD) and is referred to as DVD-RAM. FIGS. 1c and 1 d show twoexamples of a periodical modulation (wobble) of the pregroove. Thiswobble produces an extra signal in a tracking servorecorder. The wobbleis, for example, frequency-modulated and position information such as anaddress or a time code is encoded in the modulation. A writable CDsystem which is provided with position information in this way isdescribed in U.S. Pat. Nos. 4,901,300 and 5,187,699 hereby incorporatedin whole by reference. A track structure may also include, for example,regularly divided sub-patterns which periodically produce trackingsignals. Other examples of track structures are header symbols formed byoptically readable marks which are indicative of an address and indicatethe initial area for writing an information block. This description isbased on information storage in a spiral track pattern which is filledfrom the inside outwards, for example, as in a CD-ROM. The invention isalso applicable to other track patterns in which the turns are arrangedconcentrically instead of spirally, or to record carriers of differentshapes such as optical tapes.

FIG. 2 shows diagrammatically a partly written disc-shaped recordcarrier 1 provided with status information 25 according to theinvention. The area intended for information storage is indicated by anarrow 20 in a radial direction, the information being written from theinside outwards and the position information in the track structureincluding, for example, addresses ascending from the center. From thestart 26 of the area 20 intended for information storage, an initialarea 21 is uninterruptedly written with, for example, a lead-in area 12,file management information 13 and user information 14 up to an end 24.The file management information includes, for example, directories andpath tables as known from ISO 9660. Moreover, second and third writtenareas 22 and 23 are shown, which are isolated from the initial area 21and are used for storing user information. It is true that the recordcarrier 1 has a track structure as described with reference to FIG. 1,but in a standard reading device it is not usable for positioning whenthe standard reading device derives the tracking and/or positioninformation on the basis of marks. The entirely written area 21 will bereadable in each reading device because marks are uninterruptedlypresent from a radius to be minimally used (for the relevant recordcarrier type). However, when such a standard reading device must readthe isolated areas 22 or 23, for example, addressed via a read command,this device will displace a read head via a jump to a radial positioncorresponding to the address. However, since there are no marks, astandard device will not be able to position the read unit and reproduceinformation so that the device may enter an undefined state. If thetrack structure includes headers which are formed by marks, the standardreading device will, in principle, be able to read them. However, due tothe absence of intermediate marks in unwritten areas, the read unitcannot be positioned correctly above the track and tracking and readmeans cannot correctly respond. Consequently, reading of the headers inan unwritten area is unreliable. According to the invention, the recordcarrier is provided with status information 25. This status informationindicates that given areas on the record carrier are written and thestatus information is stored in a predetermined way, for example, in agiven part of the lead-in area or in the file management as shown. Areading device according to the invention, as further described withreference to FIG. 5, can read and process the status information. Thestatus information is further described with reference to the writingdevice shown in FIG. 4. In the conventional types of rewritableoptically readable record carriers provided with phase-change material,the marks once written remain present and it is not common practice touse an erasing procedure to restore the record carrier to its blank,unwritten state again. If the invention is used for a type of recordcarrier in which such an erasing procedure is used, the statusinformation should of course be adapted (i.e. updated) accordingly.

FIG. 3a shows a partly written record carrier with rewritten informationblocks in accordance with an embodiment of the invention. In addition tothe written areas 21, 22, 23 shown in FIG. 2, areas 32 and 33 arewritten contiguously to the initial area 21 after the end 24. Theinformation blocks recorded in the isolated areas 22 and 23 are writtenonce again in the contiguous areas 32 and 33. The sequence of theinformation blocks written once again can be freely chosen. In theconventional file management systems, the position of the informationblocks is indicated in the file management information. In a firstembodiment of the invention, the file management information is adaptedto the new location of the information blocks in the contiguous areas 32and 33. This has the advantage that the partly written record carriercan now be read by any standard reading device because all informationblocks are now located in the initial area and can thus be approachedvia an uninterrupted written area. In a practical embodiment, the statusinformation can be adapted by using a reading/writing device such as aDVD-RAM drive, while the information blocks can be rewritten via asoftware program in a computer system connected to the DVD-RAM drive.This program can then be taken up in the device driver of the DVD-RAMinterface or used as a separate program, for example, in the backgroundof a multitasking system. Rewriting can then take place when there areno other writing and/or reading instructions for the DVD-RAM drive. In afurther embodiment, the record carrier is provided with additionalposition information 35 at a predetermined position. This has theadvantage that the original file management information remainsunchanged. The additional position information then includes, forexample, an address translation table for translating the originaladdresses of the information blocks in the isolated areas 22 and 23 tothe new addresses of the rewritten blocks in the contiguous areas 32 and33. In the case of a reading instruction, a system drive in a readingdevice can read the address translation table and the status information25, and if the addresses to be read are outside the initial area 21, anaddress of the rewritten information block can be searched via theaddress translation table. In this case, it is an advantage that mostinformation blocks maintain their original address because, normally,the file management system positions the information blocks contiguouslyfrom the start. Consequently, only a relatively short addresstranslation table is required. In a practical embodiment, the addresstranslation table can be read and processed in a DVD drive or in theconnected computer system via device-driver software installed thereinin the conventional manner.

FIG. 4 shows a device for writing information blocks on a disc-shapedrecord carrier of a writable type, for example, magneto-optically oroptically (via phase change) writable via a beam of electromagneticradiation. During writing, marks representing the information are formedon the record carrier. The device is provided with drive apparatus 45for rotating the record carrier 1 and a write head 42 for scanning thetrack which is indicated by the track structure on the record carrier.The device is further provided with a system drive unit 46 for receivingcommands from a driving computer system or a user and for driving thedevice. To this end, the system drive unit includes, for example, amicroprocessor, a program memory and driver ports for performing theprocedures described hereinafter and for driving said elements. Thewrite head 42 is positioned radially on the track by positioningapparatus 44, for detecting position information from the trackstructure. In accordance with known tracking and focusing methods, thewrite head scans the track while, for example, a modulation is presentin the tracking signal due to the wobble in the pregroove. The trackingsignal is demodulated and the position information encoded therein isregained in the positioning apparatus 44 and passed on the system driveunit 46. The radial position of the write head can be verified via theregained position information. The information presented to the input ofthe write apparatus 41 is divided, if necessary, into information blocksand converted into a write signal for the write head 42. The writeapparatus 41 includes, for example, an error encoder and a channelencoder. The system drive unit 46 drives the positioning apparatus 44,the write apparatus 41 and the drive apparatus 45 and is equipped toperform the procedures, to be described hereinafter, for generating thestatus information.

The system drive unit 46 includes apparatus to detect whether areas arewritten and generate corresponding status information. This statusinformation is indicative of the fact whether at least one area of therecord carrier is written, the status information includes initial-areainformation which is indicative of an uninterrupted written initial areawhich extends from the start of a track pattern area intended forwriting information blocks. This initial area may be read by anystandard reading device, because no unwritten areas need to be crossedduring positioning. The status information 25 should only be adaptedwhen blank, unwritten areas right after the end 24 are written. In afirst embodiment, the initial-area information includes end-addressinformation which is indicative of the position of the end of theinitial area. The status information 25 in FIG. 2 then indicates wherethe end 24 of the initial area 21 is located, for example, by means ofan address of the last written information block. It is to be noted thatit is not important whether the information block actually includesinformation which is in use. The end address of the initial area 21 thenalways indicates the highest, ever written end. Alternatively, the startand the length of the initial area can be fixed, or the status of allrelevant areas can be fixed in a bit map. The status of further areaslocated on the record carrier can be fixed, for example, as intervals inan interval table. When the initial area grows at a given moment in sucha way that it will be contiguous to an interval already written, thelimit of the initial area can be directly shifted until after thisinterval. The interval table includes interval information which isindicative of the position of the start and end of uninterrupted writtenareas of the track pattern. In another embodiment, the status of allsub-areas is fixed in a bit map. The status information then includesbit map information which is indicative of written and unwritten areas.In this case, one bit is available for each area of a size to beminimally written in one run, while the bit of a given address on therecord carrier indicates the status. This minimal size is dependent onthe error correction used which extends across a given quantity ofinformation. For example, in a DVD, the size of an information block is32 kbyte so that for 1 bit per information block a bit map for 8 Gbytesfits in one information block. Also as an addition to the bit map, atable with written areas can be fixed in which at least the end of thefirst written area (viewed in the radial direction from the centralaperture) is given. Without an analysis of a large number of bits fromthe bit map, the size of the initial area can be read from this table.

In a first embodiment of the detection, the written state is derivedfrom the received writing instructions and possibly from successfullyperformed reading instructions. From the moment when the record carrieris introduced into the device, the system drive unit records which areasare written, for example, by using a list of addresses or a bit map asdescribed above. In the case of a writing instruction for a givenaddress, the bit corresponding to this address is set to the state whichindicates the written state. In a second embodiment, the written stateis further detected because the system drive unit reads areas of therecord carrier on its own initiative. In another embodiment, the statusinformation is also derived from the file management information presenton the record carrier, which information conventionally includes tablesstating whether addressable areas on the record carrier are free oroccupied. In this respect it is to be noted that this file managementinformation only indicates the current state, with no information beingpresent about areas written in the past and being meanwhile free again.In contrast, the status information also includes information about allareas ever written which are meanwhile free again for new data storage.The system drive unit can store the status information of a given recordcarrier in a memory. Moreover, this stored status information may beprovided with an identification of the record carrier so that the statusinformation is available from the memory after the record carrier hasbeen re-inserted into the device.

In an embodiment of the writing device, the system drive unit fixes thestatus information on the record carrier itself (i.e. writes the statusinformation onto the respective optical disk. This has the advantagethat the status information is available at each drive in which therecord carrier is written. The status information can be fixed (i.e.written to the respective record carrier) at a predetermined position onthe record carrier, for example, in or preceding the lead-in area whereno user information may be stored. Instead, the status information maybe fixed as a file for which the rules of the file management systemused must be maintained (via Directories and Path Tables). The statusinformation may be stored, for example, immediately after a change ofthe end of the initial area. In one embodiment of the device, fixing onthe record carrier is dependent on the operational circumstances. Fixingmay be performed, for example, when no other writing instructions areavailable. It is also possible to wait until a command is given to ejectthe record carrier from the device or to switch off the device. At thatmoment, the status information must first be fixed. This has theadvantage that wear due to repeated fixing can be limited. Fixing canalso be postponed so that the status information is not writtenunnecessarily often but does not trail too much in the case of anunwanted interruption such as current failure. Thus it is possible towait until at least N areas which have not been written earlier arewritten since the last fixing procedure. When N is chosen to be, forexample, 16 then, at most 15 blocks more are written than the previousstatus information indicates. In an embodiment of the device, the systemdrive unit can supplement the fixed status information, when the recordcarrier is re-inserted into the device, by reading information blockscontiguous to the initial area where at most 15 blocks can follow.Moreover, the device can attempt to read small unwritten areas, forexample, up to a length of 16 blocks and possibly adapt the statusinformation accordingly. If an uninterrupted area separated into twointervals by such a small area is incorrectly fixed in the statusinformation, the status information can be adapted to one interval. Evenif there appears to be a small gap between two written areas, the devicemay independently write this area with dummy information so that abetter uninterrupted division is also obtained.

In a further embodiment, the above-mentioned operation is combined in a“paving” procedure. The gaps between the written areas are successivelywritten in the paving procedure described hereinafter by filling allgaps in consecutive work areas from the start of the track. FIG. 3bshows diagrammatically three work areas on the record carrier 1 afterthe paving procedure has been completed, with the area from the start ofthe track being entirely written at least up to the radius of thefurthest outwardly located information block 23. A first work areaextends from the written area 21 to the radius 36 which is locatedfurther outwards. Subsequently, a second word area is indicated up to asecond further outward radius 37 and a last work area up to a thirdradius 38. The size of the work areas and hence their number is chosento be such that a work area can be filled in a limited period of time,for example, one minute.

First, the system drive unit searches and reads the location of thetrack where the initial-area information such as the end address of theuninterrupted written initial area (End of Written Area, EWA) iswritten. When the record carrier is still completely unwritten orpreviously submitted to the paving procedure, this location is stillunwritten and the location is initialized by recording the startingvalues such as, for example, EWA=0. Secondly, a work area of apredetermined length just beyond the initial area is read for detectingthe status information in this work area. The length may be, forexample, 256 or 1024 information blocks and the status of each of theseblocks is subsequently known, namely whether they are written orunwritten. When, due to formatting of the information blocks, a givennumber of blocks should always be jointly written, only the status ofsuch a group needs to be determined. This is the case, for example, whenerror correction information is determined and written for a jointnumber of blocks. Moreover, bad sectors and verification can be takeninto account. Thirdly, the still unwritten gaps in this work area arefilled with dummy information, while areas which have already beenwritten are carefully skipped. Finally, the EWA is adapted to the newsituation, whereafter the uninterrupted written initial area is enlargedwith the work area. The paving procedure is then repeated for asubsequent work area. Alternatively, the EWA may be adapted after theenlargement with a number of small work areas; this has the advantagethat the location of the EWA needs to be rewritten less frequently. Itis to be noted that the EWA can be fixed with a resolution in conformitywith the minimal work area. Alternatively, the EWA may comprise theaddress of the block which was actually last written so that asubsequent paving procedure can start from EWA when the EWA value iswritten as the last value when an eject command breaks off theprocedure.

The above-mentioned paving procedure can be performed automatically whenthe operational circumstances allow this, for example, when no externalinstructions have to be carried out. If another external instruction ispresented to the device during processing of the work area, theprocessing operation may be postponed or broken off completely. Afterthe external instruction has been carried out, the processing operationcan be resumed or restarted. In this case, of course the statusinformation within the work area should first be adapted to thesituation after the external instruction if, due to this instruction,sectors in the work area have been written. Alternatively, the pavingprocedure is started by an external instruction, for example, a partialfinalization command when the user wants to make a DVD-RAM recordcarrier suitable for use in a DVD-ROM player. In this case, all gaps upto the highest address in use must be written with dummy information. Itis advantageous to write also a small area beyond the highest address inuse so that a DVD-ROM player which jumps a bit too far upon a jump tothis address does not land in an unwritten area. The highest address inuse may be derived, for example, from the file management information orpassed along with the finalization command. The successive filling ofall gaps may be effected, for example, in the manner describedhereinbefore by repeatedly processing work areas until the highestaddress in use is reached. Another full finalization command mayindicate that the complete record carrier is to be written up to thelimit of the area intended for storing information.

In a further embodiment, the status information comprises the value ofthe Last Used Block (LUB) which is fixed at a location on the recordcarrier, for example, together with the EWA. During a writinginstruction with a higher address than the LUB, this LUB is to beadapted. It is then advantageous to rewrite the LUB before performingthe writing instruction so that, in the case of current failure, thecorrect value for the LUB is present on the record carrier directlyafter performing the writing instruction. This causes some loss ofperformance because it is necessary to write at two locations in thecase of such writing instructions, which locations will be far apartfrom each other on the record carrier. In fact, the LUB will be fixedclose to the start of the track and, in contrast, the new informationblock to be written is far remote from the start of the track. It isadvantageous to fix only an indication of the Last Used Zone (LUZ)instead of the exact address of the Last Used Block, which zones may beas large as the work areas of the finalization procedure. Theperformance loss is now considerably limited because the LUZ only needsto be written once per zone when an information block must be writtenfor the first time in a zone which is located further outwards.

A further advantage is that the paving or finalization procedure as suchdoes not need to be fixed in a standard, except for the location of theEWA on the record carrier. In fact, it is not necessary that each deviceknows such a paving procedure and performs it in exactly the same way(for example, with a given size of the work areas), because the currentsituation of the area just beyond the EWA is always read first whenperforming the procedure. This precludes the risk that areas whichcomprise information are overwritten inadvertently.

In a further embodiment, several locations are reserved for statusinformation to be written on the record carrier. For predictablychanging parameters, such as EWA or LUZ, each new value will be higherthan the previous value. The new value is now fixed in a subsequentlocation, while the first value is re-used after use of the last value.During reading, all locations are read and the highest value isdetermined, i.e. the last written and, consequently, valid value. Thishas the advantage that wear due to repeated writing of one location isnow limited by the spread across all reserved locations. Alternatively,an (ascending) serial number can be written for a parameter to bewritten, by which the last fixed and hence valid parameter is known.

Dependent on the chosen way of fixing the status information, the systemdrive knows the location of the status information or a reference to thestatus information, or it uses the file management information in knownmanner so as to reproduce the status information. The status informationmay be fixed at a predetermined position on the record carrier, forexample, in or preceding the lead-in area where no user information maybe stored. In contrast, another suitable position is near the end of thearea intended for data storage because, globally, the record carrierwill be filled from the start. When the area near the end is necessaryfor data storage when the record carrier has almost completely beenfilled, the status information will be limited to a small quantity ormay be canceled entirely because then there are (virtually) no unwrittenareas left. Instead, the status information can be fixed as a file. Inanother embodiment, for example, extra validity information in thestatus information may be stored on the record carrier. For performing afirst writing instruction, the device writes the validity information onthe record carrier, indicating that the record carrier can comprise morewritten areas and/or areas which are in use than the status on thisrecord carrier indicates. If the operational circumstances permit this,a new version of the status is fixed, whereafter the validityinformation is fixed again as the last information but now with thecontents that the status is completely up to date. If the session isinterrupted in the meantime, for example, due to current failure ormanual removal of the record carrier, the validity information on therecord carrier indicates that the status information is incomplete.

A further embodiment of the writing device is provided with rewritingmeans for rewriting, contiguously to the initial area, informationblocks which are isolated from the initial area, as described withreference to FIG. 3a. To this end, the system drive unit 46 is adaptedto detect isolated areas. Subsequently, the system drive unit will readthe block and write it once again, contiguously to the initial area butof course with an adaptation of the initial-area information in thestatus information. Moreover, the system drive unit is suitable foradapting the file management information or for taking up the originaladdress and the address after rewriting in an address translation table.In the case of a reading instruction from a driving computer system, theoriginal address will be derived from the file management information.The system drive unit will then translate this presented originaladdress into a physical address within the initial area via the addresstranslation table. In another embodiment, this translation can takeplace in the driving computer itself, which translation is then providedby a software implementation, for example, in device driver software.During rewriting, areas which are not written yet are preferably used sothat a maximal part of the record carrier is written and is thereforeaccessible to a standard reading device. If, at a later instant, an areain which a copy is written via the file management information is putinto use, the information block rewritten in this area should berewritten again in an unwritten area located at a further position butof course with a corresponding adaptation of the status information. Thesystem drive unit is adapted for this purpose and checks, in the case ofwriting instructions in the initial area, whether an area used forrewriting must be written. In that case, a new rewriting procedure isinitiated, which proceeds in the manner described previously withreference to FIG. 3a in rewriting newly written isolated areas.

The temporary status information which has not been fixed (i.e. written)yet is preferably stored in a non-volatile memory in the writing deviceso that, after termination of a current failure, the temporary statusinformation can as yet be fixed. In another embodiment, an indicationcan be fixed in the status information that the record carrier does notfully comply with the requirements of a reading device, for example,when it is “partly ROM drive prepared” and possibly a list ofinformation blocks to be rewritten can be added. Moreover, a recordcarrier in which no areas are isolated because all isolated areas arerewritten can be marked as such with “fully ROM drive prepared”.Furthermore, status information can be written at two locations duringstorage so as to have a reserve copy of these important data in the caseof damage of the first storage area.

FIG. 5 shows a reading device according to the invention for readinginformation blocks. The reading device is provided with drive apparatus45 for rotating the disc-shaped record carrier 1 and a read head 52 forscanning the track on the record carrier. The read head 52 is positionedradially on the track by positioning apparatus 44 on the basis ofsignals derived from marks on the record carrier. In accordance with theconventional Differential Phase Detection or Differential Time Detectionsystem (DPD or DTD), for example, the reflected radiation on a detector(not shown) can be collected, which detector is subdivided into 4sub-detectors. By determining phase or time differences between thesignals of the sub-detectors, the position of the scanning spot withrespect to the series of marks written in the track can be determined.In this respect, it may be noted, that such a device, intended forreading Read-Only record carriers such as, for example, a DVD-ROM, willnot be provided with apparatus for deriving tracking and/or positioninformation from a track structure on a writable record carrier. Duringreading, the signal of the read head 52 is converted into theinformation in the read apparatus 43, for example, comprising a channeldecoder and an error corrector. Moreover, the device is provided with asystem drive unit 46 which, inter alia, on the basis of a read command,will displace the read head 52 to a radial position which is located ashort distance before the area to be read (coarse positioning), andsubsequently the system drive unit will derive the current position viathe read head 52 and the positioning means 44 from position informationread from the record carrier and subsequently (fine-)position the readhead on the basis of the position information. In the reading deviceaccording to the invention, the positioning means are adapted toposition the head upon the status information. When performing a jump,the positioning means will then always position the read head above awritten part of the record carrier and then fine-position it via awritten area, if necessary, in a movement opposite to the direction ofthe jump. In an embodiment of the reading device according to theinvention, the positioning means are adapted to reject instructions forpositioning outside the initial area. This has the advantage that thedriving computer knows which instructions cannot be carried out andpossibly also why not via an error code in the rejection. Then, thereading device cannot come in an undefined state due to, for example, anendless search for marks in an unwritten area. In a further embodimentof the reading device, the system drive unit 46 is adapted to translatethe original addresses from reading instructions to the physicaladdresses of the rewritten information blocks via the translation table,as described hereinbefore. The original address has then been determinedfrom, for example, the file management information. If the originaladdress is located in the initial area, the information block has notbeen rewritten. Consequently, the translation only needs to take placeif the original address is indicative of a position outside the initialarea. In practice, the greater part of the information blocks will belocated in the initial area. This has the advantage that no translationis needed for a large number of reading instructions.

The invention may also be used for Write Once record carriers, such as,CD-R or DVD-R. With the paving procedure described above, a partlywritten DVD-R may be rendered suitable for use in other reading devicesby filling up the unwritten areas with dummy information. In such arecord carrier, the paving or finalization procedure should of courseonly be started after an external command which may be given by the userif he does not want to store further information on the DVD-R.Parameters which are indicative of the written state, such as EWA, canbe stored in a memory in the device during the procedure and/or aftercompletion in the next free location of a series of locations reservedfor this purpose on the Write Once record carrier.

FIGS. 6 and 7 shows positioner 44 and system drive unit 46 of FIGS. 4and 5 in more detail. The purpose of this figure is to illustrate theclaimed apparatus and is not required for an understanding of theinvention. The apparatus and relationships shown in this figure has beenpreviously described in this specification, in relation to a specificembodiment of the invention, thus this portion of the description willonly briefly identify the apparatus.

In FIG. 6, positioner 44 includes apparatus 61 for positioning the readand write units; apparatus 62 for detecting position information on therecord carrier; apparatus 63 for controlling the position based on themarks on the record carrier and on the status information; and apparatus64 for rejecting instructions to read and/or write data outside of theinitial area. The positioner also includes an address translator fortranslating a first address of an information block in accordance withfile management information into a second address in the initial area.This allows reading from and/or writing to blocks of information whichhave been rewritten to copy the blocks to a position contiguous with theinitial area.

In FIG. 7, the system drive unit 46 includes a microprocessor 66,programmable memory 67 and ports 68 and 69 for receiving information andproviding control signals and information. Memory 67 includes programmedapparatus for controlling the operation of CPU 65 and a copy ofinformation that has been read or will be written to the record carrier,and other information required for operations. Programmed statusapparatus 70 includes apparatus 71 for generating status information 72including an indication 73 that at least one area of the record carrierhas been written and initial-area information 74 including end-addressinformation 75 indicating the position of the end of the initial area.The status information also includes an interval table 76 with intervalinformation 77 including information 78 indicating the start and end ofuninterrupted written areas. The status information also includesbit-map information 79 defining written and unwritten areas andincluding sub-area status information 105 and indication 106 of thestart and length of initial area.

Status apparatus 70 includes apparatus 80 to write status information 73onto the respective record carrier, and apparatus 81 to preserve andprocess the, status information and write the status information to therespective record carrier depending on operational circumstancesincluding: apparatus 82 for fixing the status information when at leastN areas have been written since the last such fixing; apparatus 83 forwriting the status information when an eject command is received for therespective record carrier; apparatus 84 for writing the statusinformation when a command to turn off the device is received; andapparatus 85 for writing the status information when the end of theinitial area changes. The status apparatus also includes apparatus 86 todetermine the status information for a work area contiguous with theinitial area, and apparatus 87 for paving work areas (i.e unwrittenparts contiguous with the initial area) with information to allowreliable tracking by writing into such work areas with dummyinformation. Finally the status apparatus includes apparatus 88 formaintaining a copy of the status information in memory, and apparatus 89for detecting written areas.

Memory 67 also includes programmed rewriting apparatus 90 includingapparatus 91 for rewriting to copy information blocks which are isolatedfrom the initial area to a position contiguous with the initial area.Rewriting apparatus 90 further includes: apparatus 92 for updating thefile management information 93 to indicate the new location ofinformation on the record carrier when areas are rewritten; apparatus 94for generating additional position information 95 including an addresstranslation table 96 with information 97 for translating a first addressof information blocks outside the initial area to a second address ofinformation blocks within the initial area, such as the original addressof isolated blocks to the new address of rewritten blocks; and apparatus98 for writing the address translation table to the respective recordcarrier. File management information 93 includes: a table 99 indicatingwhich areas are free and which areas are written; directories 100; andpath tables 101. The status information also includes a record carrieridentification 102 so that multiple record carriers may be used in thesystem.

The system of the invention may include an instruction rejectionapparatus 103 for rejecting instructions to read and/or write to thearea outside of the initial area to keep the system from going into anundefined state. The instruction rejection apparatus may be located inthe system drive unit as shown, or in the positioner as shown in FIG. 6,or in another portion of the system. In this specific embodiment, thesystem also includes apparatus 104 which uses the information in addresstranslation table 96, for translating an original address of informationblocks according to the file management information that are isolatedfrom the initial area into a new address of information blocks copied toa position contiguous with the initial area.

Memory 67 may be dynamic random access memory or non-volatile memory.The above specific embodiment with programmed devices may be implementedby reading programs and information from the record carrier 1 throughports 68 or 69, into memory 67. Alternatively the devices may beimplemented by connecting a memory component 107 to communicate with CPU66 such as by inserting a memory cartridge into a slot or a non-volatilememory package into a socket.

The reading and/or writing device of the invention may include aprogrammable computer system or computer network. FIG. 8 shows computersystem 110 and programmable computer system 111 with a read and/or writeunit 112, a read unit 113 and a positioner 114, communicating through acommunications network 112. Computer 110 includes apparatus 113 forprogramming computer 111 for implementing the inventions of thisapplication. Computer 110 generates signals transferred throughcommunication network 114 to the programmable computer 111 to providethe programed apparatus of the invention. Thus if the read or write unitis subsequently connected to computer 112, then the read device and/orwrite device of the invention will be implemented, and the method of theinvention practiced.

The invention has been disclosed with reference to specific preferredembodiments, to enable those skilled in the art to make and use theinvention, and to describe the best mode contemplated for carrying outthe invention. Those skilled in the art may modify or add to theseembodiments or provide other embodiments without departing from thespirit of the invention.

Thus, the scope of the invention is only limited by the followingclaims:
 1. A writing device comprising: a write unit for writing marksrepresenting information blocks in areas of a track pattern on a recordcarrier, using a beam of electromagnetic radiation; positioning meansfor positioning the write unit with respect to the record carrierdepending on a track structure which indicates the position of the trackpattern; and status means for generating status information, the statusinformation indicating whether at least an initial area of the recordcarrier has been written, the status information indicating informationblocks not contiguous with the initial area of the record carrier thatshould not be read by a device reading the record carrier and the statusinformation indicating if duplicate information blocks contiguous withthe initial area exist for information blocks not contiguous with theinitial area, then the duplicate information blocks should be read bythe device reading the record carrier.
 2. A rewritable record carrier,comprising: a track pattern for writing marks representing informationblocks; a track structure which indicates the position of the trackpattern; and means for representing status information, the statusinformation indicating whether at least an initial area of the recordcarrier has been written, the status information indicating informationblocks not contiguous with the initial area of the record carrier thatshould not be read by a device reading the record carrier and the statusinformation indicating if duplicate information blocks contiguous withthe initial area exist for information blocks not contiguous with theinitial area, then the duplicate information blocks should be read bythe device reading the record carrier.
 3. A method comprising the stepsof: positioning a write unit on a track of a record carrier of therewritable type; writing marks representing information blocks in areasof the track pattern using a write unit and a beam of electromagneticradiation; and generating status information, the status informationindicating whether at least an initial area of the record carrier hasbeen written, the status information indicating information blocks notcontiguous with the initial area of the record carrier that should notbe read by a device reading the record carrier and the statusinformation indicating if duplicate information blocks contiguous withthe initial area exist for information blocks not contiguous with theinitial area, then the duplicate information blocks should be read bythe device reading the record carrier.
 4. A reading device comprising:read means for reading information blocks represented by opticallyreadable marks in a track pattern on a record carrier; a read unit forreading the marks using a beam of electromagnetic radiation; andpositioning means for positioning the read unit depending on the marksand depending on status information, the status information indicatinginformation blocks not contiguous with the initial area of the recordcarrier that should not be read by a device reading the record carrierand the status information indicating if duplicate information blockscontiguous with the initial area exist for information blocks notcontiguous with the initial area, then the duplicate information blocksshould be read by the device reading the record carrier.
 5. An apparatusfor providing signals for programming a programmable system comprising:write status means for generating status information, the statusinformation indicating whether at least an initial area of a track of anoptical record carrier has been written, the status informationindicating information blocks not contiguous with the initial area ofthe record carrier that should not be read by a device reading therecord carrier and the status information indicating if duplicateinformation blocks contiguous with the initial area exist forinformation blocks not contiguous with the initial area, then theduplicate information blocks should be read by the device reading therecord carrier; and compliance status means for generating compliancestatus information which indicates whether the optical record carrierhas been written to fully comply with requirements of a reading device.6. The writing device of claim 1, further comprising: wherein the statusinformation includes initial-area information indicating the extent ofthe initial area, the initial area extending contiguously from a startof a track pattern area intended for writing information blocks; whereinthe initial-area information includes end-address information indicatingthe end of the initial area; wherein the status information includesinterval information indicating the position of the start and the end ofa contiguous written area of the track pattern, the contiguous writtenarea including the initial area; wherein the status information includesbit map information identifying written and unwritten areas; wherein thestatus means are adapted to write the status information on the recordcarrier; wherein the status means are adapted to preserve and processthe status information during a period of time and to write the statusinformation after the period of time depending upon operationalcircumstances; wherein the operational circumstances include a writingof at least N areas not written since the previous writing of statusinformation, a command to eject the record carrier from the device or acommand to switch off the device; wherein the status means are adaptedto determine the status information for a work area contiguous to theinitial area and to write the unwritten parts of the work area withdummy information; means for rewriting, contiguously to the initialarea, information blocks which are isolated from the initial area;wherein the rewriting means are adapted to update file managementinformation indicating the position of the information blocks on therecord carrier and to indicate the position of the rewritten informationblocks; the rewriting means are adapted to generate an addresstranslation table on the record carrier, the address translation tableincludes information for translating the original address of therewritten information blocks into the new address of the rewritteninformation after the rewriting operation; wherein the write unitincludes means for reading the information blocks represented by themarks and the positioning means positions the write unit with respect tothe record carrier depending on the marks and status information readfrom the record carrier; wherein the positioning means are adapted toreject at least some instructions for positioning outside the initialarea for reading or writing information; means for translating dependingon an address translation table, a first address of information blocksin accordance with file management information into a second address inthe initial area, when the first address indicates a position outsidethe initial area; and reading means for using the write unit and thebeam of electromagnetic radiation for reading the marks.
 7. The recordcarrier of claim 2: wherein the status information includes initial-areainformation indicating the extent of the initial area, the initial areaextending contiguously from a start of a track pattern area intended forwriting information blocks; wherein the initial-area informationincludes end-address information indicating the end of the initial area;wherein the status information includes interval information indicatingthe position of the start and the end of a contiguous written area ofthe track pattern, the contiguous written area including the initialarea; and wherein the status information includes bit map informationidentifying written and unwritten areas.
 8. The method of claim 3,further comprising the steps of: wherein the status information includesinitial-area information indicating the extent of the initial area, theinitial area extending contiguously from a start of the track patternarea intended for writing information blocks; wherein the statusinformation includes end-address information which indicates the end ofthe initial area; wherein the status information includes intervalinformation which indicates the position of the start and the end of acontiguous written area of the track pattern, the contiguous writtenarea including the initial area; wherein the status information includesbit map information which identifies written and unwritten areas;writing the status information on the record carrier; preserving andprocessing the status information during a period of time and thewriting of the status information occurs after the period of timedepending upon operational circumstances; wherein the operationalcircumstances include a writing of at least N areas not written sincethe previous writing of status information, a command to eject therecord carrier from the device or a command to switch off the device;determining the status information for a work area contiguous to theinitial area; writing dummy information onto the unwritten parts of thework area; rewriting, contiguously to the initial area, informationblocks which are isolated from the initial area; wherein the rewritingincludes updating file management information indicating the position ofthe information blocks on the record carrier, to indicate the positionof the rewritten information blocks; generating an address translationtable on the record carrier, the address translation table includesinformation for translating the original address of the rewritteninformation blocks into the new address of the rewritten informationafter the rewriting operation; rejecting instructions for positioningoutside the initial area; and translating, depending upon an addresstranslation table, a first address of information blocks in accordancewith file management information into a second address in the initialarea, in case the first address is indicative of a position outside theinitial area.
 9. The reading device of claim 4, further comprising:wherein the status information includes initial-area informationindicating the extent of the initial area, the initial area extendingcontiguously from a start of a track pattern area intended for writinginformation blocks; wherein the initial-area information includesend-address information indicating the end of the initial area; whereinthe status information includes interval information indicating theposition of the start and the end of a contiguous written area of thetrack pattern, the contiguous written area including the initial area;wherein the status information includes bit map information identifyingwritten and unwritten areas; status means adapted to write the statusinformation on the respective record carrier and preserve and processthe status information during a period of time and to write the statusinformation after the period of time depending upon operationalcircumstances; wherein the operational circumstances include a writingof at least N areas not written since the previous writing of statusinformation, a command to eject the record carrier from the device or acommand to switch off the device; wherein the status means are adaptedto determine the status information for a work area contiguous to theinitial area and to write the unwritten parts of the work area withdummy information; means for rewriting, contiguously to the initialarea, information blocks which are isolated from the initial area;wherein the status means are adapted to update file managementinformation indicating the position of the information blocks on therecord carrier and to indicate the position of the rewritten informationblocks; wherein the status means are adapted to generate an addresstranslation table on the record carrier, the address translation tableincluding information for translating the original address of therewritten information blocks into the new address of the rewritteninformation after the rewriting operation; wherein the positioning meansare adapted to reject at least some instructions for positioning outsidethe initial area for reading or writing information; and wherein thestatus means include means for translating depending on an addresstranslation table, a first address of information blocks in accordancewith file management information into a second address in the initialarea, when the first address indicates a position outside the initialarea.
 10. The signal providing signals apparatus of claim 5, furthercomprising: initial status means for generating initial-area statusinformation indicating the extent of the initial area, the initial areaextending contiguously from a start of a track pattern area intended forwriting information blocks; wherein the initial-area status informationincludes end-address information which indicates the end of the initialarea; interval status means for generating interval status information,the interval status information indicating the position of the start andthe end of a contiguous written area of the track pattern, thecontiguous written area including the initial area; bit map status meansfor generating bit map status information, the bit status informationidentifying written and unwritten areas of the track; status write meansfor writing the status information on the respective record carrier;operational means for preserving and processing the status informationduring a period of time and to write the status information after theperiod of time depending upon operational circumstances; wherein theoperational circumstances include a writing of at least N areas notwritten since the previous writing of status information, a command toeject the record carrier from the device or a command to switch off thedevice; dummy writing means for determining the status information for awork area contiguous to the initial area and for writing the unwrittenparts of the work area with dummy information; rewriting means forrewriting, contiguously to the initial area, information blocks whichare isolated from the initial area; wherein the rewriting means isadapted to update file management information indicating the position ofthe information blocks on the record carrier and to indicate theposition of the rewritten information blocks; wherein the rewritingmeans is adapted to generate an address translation table on the recordcarrier, the address translation table including information fortranslating the original address of the rewritten information blocksinto a new address of the rewritten information after the rewritingoperation; rejecting means for rejecting instructions positioned outsidethe initial area; and translating means for translating, depending uponan address translation table, a first address of information blocks inaccordance with file management information into a second address in theinitial area, in case the first address is indicative of a positionoutside the initial area.
 11. A program storage device readable bymachine, tangibly embodying a program of instructions executable by themachine to perform method steps for providing signals for programming aprogrammable system, the method steps comprising: positioning a writeunit depending on a track structure which indicates a track pattern onan record carrier of the rewritable type; writing marks representinginformation blocks in areas of the track pattern via a write unit and abeam of electromagnetic radiation; and generating status information,the status information indicating whether at least an initial area ofthe record carrier has been written, the status information indicatinginformation blocks not contiguous with the initial area of the recordcarrier that should not be read by a device reading the record carrierand the status information indicating if duplicate information blockscontiguous with the initial area exist for information blocks notcontiguous with the initial area, then the duplicate information blocksshould be read by the device reading the record carrier.